html,body {
  font-size: 37.5px;
}
body * {
  box-sizing: border-box;
  flex-shrink: 0;
}
body {
  font-family: PingFangSC-Regular, Roboto, Helvetica Neue, Helvetica, Tahoma, Arial, PingFang SC-Light, Microsoft YaHei;
}
button {
  margin: 0;
  padding: 0;
  border: 1px solid transparent;
  outline: none;
  background-color: transparent;
}
button:active {
  opacity: 0.6;
}
.flex-col {
  display: flex;
  flex-direction: column;
}
.flex-row {
  display: flex;
  flex-direction: row;
}
.justify-start {
  display: flex;
  justify-content: flex-start;
}
.justify-center {
  display: flex;
  justify-content: center;
}
.justify-end {
  display: flex;
  justify-content: flex-end;
}
.justify-evenly {
  display: flex;
  justify-content: space-evenly;
}
.justify-around {
  display: flex;
  justify-content: space-around;
}
.justify-between {
  display: flex;
  justify-content: space-between;
}
.align-start {
  display: flex;
  align-items: flex-start;
}
.align-center {
  display: flex;
  align-items: center;
}
.align-end {
  display: flex;
  align-items: flex-end;
}

@numOfClasses: 5;

.generate-classes(@i) when (@i > 0) {
  .mt-@{i} {
    margin-top: 4px * @i;
  }
  
  .mb-@{i} {
    margin-bottom: 4px * @i;
  }
  .ml-@{i} {
    margin-left: 4px * @i;
  }
  .mr-@{i} {
    margin-right: 4px * @i;
  }
  
  .generate-classes(@i - 1);
}

.generate-classes(@numOfClasses);
